Performant overlap N/2 continuous cache

bucketCache.ts

export class BucketCache<T> {
  private bucket1: Map<string, T>;
  private bucket2: Map<string, T>;
  private currentBucket: Map<string, T>;

  constructor(private readonly N: number) {
    this.bucket1 = new Map();
    this.bucket2 = new Map();
    this.currentBucket = this.bucket1;
  }

  get(key: string): T | undefined {
    const value = this.currentBucket.get(key);
    if (value !== undefined) {
      return value;
    }

    const otherBucket =
      this.currentBucket === this.bucket1 ? this.bucket2 : this.bucket1;
    return otherBucket.get(key);
  }

  set(key: string, value: T): void {
    if (this.currentBucket.size === this.N / 2) {
      const otherBucket =
        this.currentBucket === this.bucket1 ? this.bucket2 : this.bucket1;
      this.currentBucket = otherBucket;
      this.currentBucket.clear();
    }

    this.currentBucket.set(key, value);
  }
}